Readily adjustable pressure switch



Feb 20, 1962 M. PACKER ETAL 3,022,395

READILY ADJUSTABLE PRESSURE SWITCH Filed Sept. l0, 1959 ATTORNEY UnitedStates Patent O M 3,022,396 READILY ADJUSTABLE PRESSURE SWITCH MortonPacker, 76 Kingsley Drive, Yonkers, N.Y., and James R. Arcara, 597 NorthAve., New Rochelle, N.Y. Filed Sept. 10, 1959, Ser. No. 839,153 2Claims. (Cl. 200-83) The present invention relates to a pressureresponsive switch and, in particular, to a switch adapted to indicatethe change of fluid or vapor pressure from a preselected value in ahydraulic, lubricant or cooling supply system for internal combustionengines employed in land, air or sea vehicles.

In the normal use of small craft boats propelled by inboard engines, theoperator of the craft learns from experience to listen to the noise ofthe boat engine during its operation. Should the engine noise deviate orchange from that normally expected of it, the operator, if he isprudent, will stop the engine to ascertain its trouble if any.Heretofore, this technique remained as the one reliable method forascertaining within the very short time between commencement of troubleand resulting damage whether the lubricating or cooling system of theengine is subject to malfunction. However, should the craft operatormisjudge or fail to recognize the audible warning caused by unusualengine noise and thus fail within a short period of time, perhaps threeto five minutes, to stop the engine and repair the trouble or take othernecessary steps, costly destruction of the engine usually results. Notinfrequently, such malfunctions have led to dangerous explosions, freand even loss of a boat. A1- though attempts have been made to providecrafts with malfunction warning systems to guide the operator, inparticular the inexperienced boat operator, these systems heretoforehave proved unsatisfactory.

It is the principal object of the invention to provide a pressureresponsive switch which is reliable, simple and economical With respectto construction and operation, and which switch is adaptable forindicating malfunctions in a lubricating, cooling or hydraulic supplysystem for an engine and Which switch is particularly suitable forproviding warning alarms with respect to engine system malfunctionbefore serious trouble arises.

It is a further object of the present invention to provide a malfunctionWarning system adaptable as a normally open electrical contact pressureswitch during operation, the operation of which is regulated by amovable diaphragm. A switch in accordance with the invention is readilyadjustable for operation over a Iwide range of pressures becauseactivation of the diaphragm is controlled by its thickness and the sizeof its return spring. The switch is further characterized byinstantaneous actuation upon malfunction of a pressure system and isunaffected by the iluid material flowing in the pressure system, that isto say, the switch is adaptable to sense uids or vapors such as oils,water, chemicals or any other medium capable of causing displacement ofa pressure responsive diaphragm.

It is a further object of the present invention to provide a pressuresensitive switch for small craft boats and adapted to sense continuouslypressure of the engine cooling or lubricant system, and hence eliminatesthe need of constant vigilance over the system. The switch is readilyadapted to provide an audible or other type of warning signalinstantaneously upon malfunction of the cooling or lubricant system ofthe boat engine. The switch is explosion proof and does not introduceany boat battery drain when the system is not indicating malfunction.The switch is equally adaptable for high voltage sources as well as lowvoltage sources and circuits, wherein its current rating may beregulated by 3,022,396 Patented Feb. 20, 1962 increasing or decreasingthe amount of material making contact.

Further objects and advantages will become apparent from the followingdescription of the invention taken in conjunction with the figures, inwhich:

FIG. l illustrates an elevation View, partly in section, of a switch inaccordance with the invention; and

FIG. 2 illustrates the contact portion of the switch in make contactposition.

Switch 10 is constituted by a housing made of an upper portion 11 and alower portion 12 held together by spaced pairs of screw bolts and nuts,such as 13 and 14, one pair is shown in FIG. 1. In assembledrelationship, the housing defines an interior chamber 15. A flexibledisc-shaped diaphragm 16 and a juxtaposed relatively rigid washer 17 aresupported at the top of chamber 15 wherein the contiguous peripheraledges of diaphragm 16 and washer 17 are clamped in an annular grooveformed along chamber 15 by the assembled housing portions. Theperipheral edges of diaphragm 16 and washer 17 are held in clamped fixedposition by annular flanges 18a, 18b of the opposed coacting housingportions 11, 12. Washer 17 is dish shaped to form an annular depressedseat provided with a central opening 19 to support an electricalinsulator member 20 having stepped diameter sections. The upper diametersection has a downward facing annular flange surface 21 'which restsupon the inner ledge of washer 17. Member 20 is axially dimensioned sothat its top surface 22 is in pressed contact with diaphragm 16. Aspring retainer 23 is mounted over the lower or smallest diametersection of member 20. Retainer 23 is spring loaded to bear against thedownwardly facing confronting annular flange surface 24 of member 20. Aspring 25 is held in compression between spring retainer 23 and a secondspring retainer 26 at the lower end of the spring. Spring 25 is at alltimes in electrical contact with retainers 23, 26 since these elementsare also a part of an electrical circuit, as will be seen hereinafter.Spring retainer 26 rests upon the top of an insulated bushing 27, whichbushing has a downwardly projecting cylindrical portion carried in theinternal bore of a sleeve 28. Sleeve may be made of any suitablematerial. Sleeve 28 is provided with an outer threaded surface 29 forengaging a threaded surface in a through opening in the bottom wall ofhousing portion 12. Retainer 26 is clamped against the ange of bushing27 by the overlapping head of a screw bolt 30, which bolt extendsthrough the bore of bushing 27 and also through the bore of a secondbushing 31 having a longer cylindrical portion which is also carried inthe internal bore of sleeve 28. Bushing 31 is also of insulatingmaterial. The confronting ends of the two bushings 27, 31 are spacedapart in the internal bore of sleeve 28. The lower end of bolt 30carries a pair of nuts 32 for clamping an electrical wire lug 33 thereatand also for clamping bushing 31 against a bottom knob flange 34 ofsleeve 28. Lug 33 is connected electrically in series to an electricalsource 34, such as D.C. battery, Warning means 36, such as a light oralarm, and then ground at 37. Bolt and nut 13, 14 at the top of thehousing is also grounded. When the electrical circuit is closed by thecontact of retainer 23 and washer 17, the alarm or light 36 will providea warning. The electrical circuit includes bolt 13, housing portion 12,Washer 17, retainer 23, spring 25, retainer 26, bolt 30, lug 33, battery35, warning means 36 and ground 37. Consequently, the aforesaid housingportion, washer, retainers, spring, bolts constituting the switchstructure are made of suitable electrical conducting material. Sleeve 28and its assemblage is held to housing portion 12 by a nut 41.

Housing portion 11 has an internal chamber 38 communicating by way ofpassage 39 with the hydraulic coolant or vapor system to be sensed byswitch 10. Accordingly, nipple 40 is adapted for attachment to thepressure system. Chamber 33 is on the upper side of diaphragm 16 andwhen switch 1G is attached to the pressure system, chamber 3S fills withthe liquid or vapor and thus is subject to the pressure of the udsystem, which pressure acts upon diaphragm 16 to ileX same downwardly.It will be understood that diaphragm 16 is so designed and, if desired,also washer 17, to seal chamber 38 from the lower portion of switch lilwhen the peripheral edges of diaphragm and washer are clamped by flanges13a, 181). The midsection 20a of member 20 is of such axial length toprevent normally electrical contact of washer 17 and retainer 23 whendiaphragm 16 exes downwardly to seat ange face 21 of member 20 on washer17.

In operation, the uid pressure is sensed in upper chamber 38 at alltimes during operation of the engine. This pressure urges diaphragm 16to iiex downwardly wherein diaphragm 16 in turn bears against insulatingmember 20 and forces same downwardly whereby retainer 23 assumes theposition illustrated in FIG. 1. The electrical circuit is thus openbecause the two contact members thereof 17, 23 are spaced apart. Whenthe pressure falls below a preselected value, and spring Z is adjustedto expand at this value of pressure, the pressure against the upper sideof diaphragm 16 becomes less than the upward directed force of thepreloaded spring Z5. Spring 25 then raises insulated member 20 o itsseat in washer 17 and diaphragm 16 exes upwardly. This action bringsretainer 23 in electrical contact with washer 17, whereby the warningsignal, a light or alarm, goes on. It will be noted that the warningsignal goes on as soon as the pressure in the system drops below itspreselected value. Increase in pressure of the system above such valuewill instantaneously restore switch to its initial or normal oicondition since diaphragm 16 will then ex downwardly against spring 2Sto push insulator body 20 downward to disengage the contacting members17, 23 and thus break the electrical circuit.

One advantage of switch 10 is that it may be used with any type ofpressure system and n'eed not be designed for a specific engine becausethe critical pressure at which spring 25 will respond may be adjusted bythe boat, vehicle or aircraft operator by manually turning knob 34 onsleeve 28. Assuming a clockwise rotation, sleeve 28 and its attachedassembly of bushings 27, 31, nuts 32, retainer 26 and bolt 30 will moveup into housing chamber 1S which adds additional compression to spring2S and thus increases its preload. In contrast, turning of knob 34 inthe other direction lowers the force of preload. The pressure level atwhich spring 25 will become effective to raise diaphragm 16 andinsulating body 20 from the position shown in FIG. 1 will be larger fora greater preload, that is to say, the contacting members 17, 23 willclose at a higher pressure level than for a lower preload imparted tospring 25. Similarly, turning of sleeve 2S counterclockwise lowers thepreload so as to result in a warning of at a lower pressure level.

ln addition, the resiliency of spring 25, its thickness and length, aswell as the resiliency of diaphragm 16 may be selected to provide aparticular pressure range for switch operation, whereby pressures over awide range may be sensed and controlled by a particular design for thespring and diaphragm. Upon a withdrawing rotation of sleeve 28 and itsassemblage from chamber 15, it is desirable that retainer 26 avoidelectrical contact with housing portion 12. Consequently, bushing 27 isprovided with an enlarged flange at its top end so that maximum sleevewithdrawal halts upon bushing 27 bearing against the housing and forthis purpose it is convenient that the insulated members 27, 31 separateelements. The material constituting diaphragm 16 will be chosen toaccommodate type of tluid that is being sensed. Switch it) has beenshown as a device for responding to a drop in a fluid pressure systembelow a preselected value. In the same manner, the switch may beemployed to indicate the rise of pressure above the preselected value.In this instance, the warning light will turn off above a criticalpressure value. In the irst example, i.e., in sensing a pressure dropbelow a critical value, there is no current drain during normaloperation of switch 10 except when a warning is provided. The currentcapacity of the switch circuit may be varied, for example by suitablyselecting the material or diameter of spring 25 or by changing area ofcontact made by elements 17, 23. Although the switch has been describedwith respect to application to a boat, it is equally evident that it isof equal use in systems employed in land vehicles and aircraft.

It is intended that all matter contained in the above description orshown in the accompanying drawings shall be interpreted as illustrativeand not in a limiting sense.

What is claimed is:

l. A pressure sensing switch for making an electrical contact inresponse to a change of pressure of a fluid comprising, a frame havingan upper and a lower portion, said frame portions having operativelyengaging annular anges, a diaphragm clamped between said ilanges, anelectrically conductive washer formed also clamped between said annularilanges and having a seat extending into the lower part of said frame,an insulating body normally seated in said seat formed by said washer,said insulating body abutting against a first side of said diaphragm,means adapted to accommodate the variablepressure fluid in the upperpart of said frame and against the second side of said diaphragm, anelectrically-conductive and selectively preloaded spring located in thelower portion of said frame, the upper end of said compression springacting against said insulating body and urging it towards saiddiaphragm, an electrically conductive member movable with saidinsulating body and in electric contact with said spring, said memberforming the movable part of a normally open electric contact, said seatfor said insulating body forming the fixed part of said electriccontact, means securing the lower end of said spring relatively xed withrespect to the lower frame portion and also for selectively preloadingsaid spring and including a tubular member having an outer threadedportion engaging a threaded hole in said lower frame portion whereinsaid tubular member may be axially adjusted in either direction alongthe spring axis, said tubular member having a through bore, saidthreaded hole being located adjacent the lower end of said spring, thelower end of said tubular member extending exteriorly of said lowerframe portion, a first insulator bushing extending part way into saidtubular member bore from the interior side of said lower frame portion,said first bushing having a flange overlapping the upper end of saidtubular member for limiting projection of said bushing into said tubularmember bore, a second bushing having a flange overlapping the lower endof said tubular member for limiting the amount of projection of saidsecond bushing into said tubular member bore, a conductive retainerresting on said first bushing, the lower end of said spring being seatedon said retainer and urging same against said rst bushing, said retainerand bushings having aligned openings, a conductive member having anupper end overlapping said retainer, said conductive member extendingthrough the aligned openings of said retainer and bushings and having alower end projecting exteriorly of said lower frame portion forconnection with one side of an electrical signal source the other sideof which is connected to said electrical conductive washer, saidconductive member making electrical contact with said spring and beingelectrically insulated from said frame by said bushings, a threadedsurface on the lower end of said conductive member, a nut engaging saidlast-mentioned threaded surface and overlapping said second bushingflange and means for threadedly locking said tubular member in a desiredposition axially in either direction along said spring axis, saidpreloading assemblage being clamped together by drawing said nut upagainst said second bushing ange as said irst bushing flange is pulledagainst the upper end of said tubular member, said spring expands tomove said insulating body towards said diaphragm to cause said movableconductive member to contact said conductive washer for closing thenormally open switch when the pressure exerted by the preloaded springagainst said diaphragm exceeds the pressure exerted by the uid on saiddiaphragm.

2. A pressure sensing switch for making an electrical contact inresponse to a change of pressure of a fluid comprising, an enclosedhousing of electrical conducting material, a diaphragm supported in saidhousing and detining a pair of chambers on opposite sides of saiddiaphragm and in said housing, spring means in one chamber and having afirst end adjustably xed with respect to said housing and the other endadapted to act upon one side of said diaphragm, the plane of saiddiaphragm being at an angle to the axis of said spring and the otherside of said diaphragm being exposed to the other chamber, means forcoupling the iuid into said other chamber wherein said spring impartinga preload against said diaphragm in opposition to the pressure exertedthereon by said fluid, and an electrical contact relatively fixed withrespect to said housing portion and adapted to make electrical closedcontact with respect to said spring upon movement of said spring inresponse to a fluid pressure of preselected value, means for selectivelypreloading said spring including a tubular member having an outerthreaded portion engaging a threaded hole in said housing wherein saidtubular member may be axially adjusted in either direction along thespring axis, said tubular member having a through bore, said threadedhole being located adjacent the first end of said spring, the lower endof said tubular member extending exteriorly of said housing, a rstinsulator bushing extending part way into said tubular member bore fromthe interior side of said housing, a second insulator bushing extendingpart way into said tubular member bore from the exterior side of saidhousing, said second bushing having a ange overlapping the lower end ofsaid tubular member for limiting the amount of projection of said secondbushing into said tubular member bore, said first bushing having ailange overlapping said tubular member for limiting its projection intosaid tubular member bore, a conductive retainer resting on said rstbushing, the iirst end of said spring being seated on said retainer andurging same against said rst bushing, said retainer and bushings havingaligned openings, a conductive member having an upper end overlappingsaid retainer, said conductor member extending through the alignedopenings of said retainer and bushing and having a lower end projectingexteriorly of said housing for connection with one side of an electricalsignal source the other side of which is connected to said housing, saidconductive member making electrical Contact with said spring and beingelectri' cally insulated from said housing of said bushings, the lowerend of said conductive member having a threaded surface, a nut engagingsaid conductive member threaded surface and overlapping said secondbushing ange, and means for threadedly locking said tubular member in adesired position axially in either direction along said spring axis,whereby the preloading assemblage is clamped together by drawing saidnut up against said second bushing ange as said rst bushing flange ispulled up against the adjacent end of said tubular member.

References Cited in the le of this patent UNITED STATES PATENTS2,698,887 Shaw Jan. 4, 1955 2,744,977 Lombard et al. May 8, 19562,783,324 Brown et al Feb. 26, 1957 2,898,418 Byam Aug. 4, 1959

